A hacker can theoretically deplete everyone's wallet, or exploit all the coins available, or do other global destructive things in a short order. Therefore, Bitcoin will be worth zero if we are not careful.
Yes, if Bitcoin is found to have a serious flaw and cannot reasonably be useful as a medium of exchange and/or a store of value, then it is worth absolutely nothing since it has no other purpose. (Unless it can be fixed before serious damage occurs. Or reversed altogether.) However, I do not think the people of Venezuela take solace by the fact that at least their paper money can be used as a cheap fuel for a fire, or make paper purses, when things get bad.
